Finding "init_module" high stack usage problems is challenging when there
are over 1600 "init_module" functions in the kernel tree, so make
checkstack.pl print out the filename where the stack usage occurs.  This is
useful for code built as loadable modules.

For built-in code, it just prints the kernel image file name, like
"vmlinux".  Examples:

(before patch:)
0x0000000d callback:					1928
0xffffffff81678c09 huft_build:				1560
0x0018 init_module:					1512

(after patch:)
0x0000000d callback [divacapi]:				1928
0xffffffff81678c09 huft_build [vmlinux]:		1560
0x0018 init_module [hdaps]:				1512

Also change one if-series to use elsif to cut down on unneeded tests.
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Acked-by: Joern Engel <joern@wh.fh-wedel.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>